Eager iPhone 5 buyers from Singapore to New York lined up Friday outside Apple retail stores to purchase the U.S. technology giant's latest smartphone.

In downtown Sydney, some fans waited outdoors for three days to get the mobile device. In Hong Kong, Apple staff chanted "iPhone 5! iPhone 5!" and high-fived customers as they were escorted into the store one-by-one.

Would-be iPhone buyers in Munich braved near-freezing temperatures as they lined up at the city's Apple store, days ahead of time, one man calling the experience "definitely something special." Anxious buyers even lined up in Paris, where some Apple store employees went on strike, demanding better benefits.

Though it initially received lukewarm reviews, and has been criticized for a map application with errors and is missing geographical information, Apple says there has been record demand for the iPhone 5. It received more than 2 million pre-orders in the first 24 hours after being unveiled, double the figures for the previous version. Analysts expect Apple to sell as many as 10 million of the new phones by the end of September.

The new device is taller, lighter, slimmer, and has a bigger screen than its predecessor. It can also operate on faster mobile networks.

Meanwhile, Apple's rival, Samsung Electronics, moved to put a damper on the iPhone's debut. The South Korea-based company said Friday it planned to add the iPhone 5 to a patent infringement case as part of a long-running global legal battle between the rival tech giants.

Apple and Samsung are involved in a series of patent disputes spread across four continents. They are battling for dominance in a smartphone industry estimated to be worth more than $200 billion last year.